Contact system

ABSTRACT

The power semiconductor module comprises a module housing having a conductive cover plate ( 2 ) and a conductive baseplate and also an insulating housing wall ( 3 ) arranged between the cover plate and the baseplate. A power semiconductor circuit is accommodated in the module housing. Two terminals ( 5, 6 ) of the power semiconductor circuit are led out of the module housing, a first ( 5 ) of the at least two terminals being provided for the contact connection of the cover plate. The two terminals ( 5, 6 ) are arranged on opposite areas of a printed circuit board ( 4 ) led out of the module housing, which printed circuit board can be contact-connected by means of a standard connector.  
     The power semiconductor module according to the invention has improved contacts with regard to stability and inductance.

TECHNICAL FIELD

[0001] The invention relates to the field of power electronics. It isbased on a power semiconductor module in accordance with the preamble ofpatent claim 1.

PRIOR ART

[0002] So-called “hockey puck” semiconductor modules are semiconductormodules which are used for example in a stack comprising a plurality ofmodules, the modules generally having the form of a hockey puck, i.e.essentially cylindrical with two parallel opposite base areas. The baseareas are formed in electrically conductive fashion and connected to thepower or main electrodes (emitter, collector) of the semiconductors,while the side wall between the base areas is formed in electricallyinsulating fashion. In a stack with a plurality of series-connectedmodules, a heat sink is in each case arranged between two respectivemodules, in the main current path. For the control and monitoring of thepower semiconductor elements, a control terminal (gate) and an auxiliaryterminal (auxiliary emitter) are in each case led out of the modulehousing. In the case of conventional “hockey puck” modules, saidterminals comprise projecting pins, the auxiliary terminal beingsoldered onto one base area (emitter).

[0003] These pins can easily break off under the action of force. Thesoldering point can likewise be damaged. In addition, the inductancebetween the pin-like contacts is relatively high.

[0004] EP 0 772 235 discloses a semiconductor module comprising asemiconductor circuit composed of IGBTs in an electrically insulatedhousing. Connected to the main electrodes of the IGBTs are two powerterminals which are led out of the module housing through a side wall.The power terminals are essentially formed as planar plates which arearranged parallel to one another in a manner isolated by an insulatinglayer. A control terminal of the IGBTs is led out of the module throughthe side wall at another location.

BRIEF SUMMARY OF THE INVENTION

[0005] The object of the invention is to provide a power semiconductormodule of the type mentioned in the introduction which is improved withregard to the stability of the contacts and the inductance between thecontacts.

[0006] This object is achieved by means of a power semiconductor modulehaving the features of patent claim 1.

[0007] The core of the invention is that the two terminals of the powersemiconductor circuit which are led out of the module housing arearranged on opposite areas of a printed circuit board (PCB) which is ledout of the module housing, and that the printed circuit board is fixedto the cover plate by fixing means in a force-locking manner, so thatthe cover plate terminal arranged between the printed circuit board andthe cover plate is electrically conductively connected to the coverplate, the fixing means advantageously being arranged in the region ofthe connection location.

[0008] As a result, the terminals have increased stability inconjunction with lower inductance. Furthermore, an optimum electricalconnection between the cover plate and the cover plate terminal isensured.

[0009] The cover plate and/or the cover plate terminal advantageouslyhave a knurl in the region of the connection location. As a result, theelectrical connection is additionally improved. A more reliableelectrical contact over a longer time can thus be achieved even undervariable conditions (temperature, moisture).

[0010] In a further preferred embodiment of the power semiconductormodule according to the invention, the cover plate and the printedcircuit board each have at least two projections. A respectiveprojection of the cover plate and of the printed circuit board arearranged one above the other and the fixing means are arranged in theregion of the projections. In addition, the printed circuit board has atleast one further projection between the two projections.

[0011] The two projections of the cover plate ensure that the furtherprojection of the printed circuit board is protected from impacts. Saidprojection is advantageously formed in an essentially rectangularfashion in order that it can be contact-connected by means of aconventional connector.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A detailed description of the invention is given below on thebasis of exemplary embodiments illustrated in the drawings, in which:

[0013]FIG. 1 shows, in a diagrammatic illustration, a powersemiconductor module according to the invention, with a cover plate anda printed circuit board,

[0014]FIG. 2 shows part of a power semiconductor module according toFIG. 1, with the cover plate and a first embodiment of the printedcircuit board,

[0015]FIG. 3 shows a view of a section through the power semiconductormodule according to FIG. 2 taken along III-III,

[0016]FIG. 4 shows a view of a section through the power semiconductormodule according to FIG. 2 taken along IV-IV,

[0017]FIG. 5 shows a view from above of a second embodiment of theprinted circuit board according to FIG. 2, and

[0018]FIG. 6 shows a view from below of the printed circuit boardaccording to FIG. 5.

WAY OF EMBODYING THE INVENTION

[0019] In all the figures, identical reference symbols relate toidentically acting parts.

[0020] The power semiconductor module in FIG. 1 comprises a powersemiconductor circuit 1 composed of two power semiconductors. Thefunction and the construction of the power semiconductor circuit arearbitrary and not relevant to the invention. Thus, by way of example, aplurality of semiconductor elements may be combined in submodules thatcan be prefabricated.

[0021] The power semiconductor circuit 1 is accommodated in a modulehousing essentially comprising an electrically conductive cover plate 2,an electrically conductive baseplate 9 and electrically insulatinghousing walls 3 arranged in between.

[0022] Power or main terminals of the power semiconductor circuit 1 areelectrically conductively connected to the conductive cover plate andbaseplate as in the case of conventional “hockey puck” modules.

[0023] Control signals for the power semiconductors, for example gatecontrol signals for an insulated gate bipolar transistor (IGBT) arepassed from the housing via a busbar and a control terminal conductor 6.

[0024] According to the invention, the control terminal conductor 6 isarranged on one side of a printed circuit board 4 that is metallized onboth sides. Situated on the other side of the printed circuit board isthe cover plate terminal conductor 5, which is electrically conductivelyconnected to the cover plate 2.

[0025]FIG. 2 shows part of the power semiconductor module according tothe invention as viewed from above.

[0026] The printed circuit board 4 that is metallized on both sides isarranged between the housing wall 3 and the cover plate 2. The coverterminal conductor 5 is situated on the upper side facing the coverplate. Two control terminal conductors 6 are situated on the lower sidefacing the housing wall.

[0027] The cover plate 2 has two projections 21 projecting beyond themodule housing edge. As can be seen from FIG. 3, the printed circuitboard has two corresponding projections 41 arranged below theprojections 21 of the cover plate. The projections 21 and 41 areconnected to a fixing means 7, for example a rivet or a screw. Anelectrically conductive connection is thereby produced between the coverplate terminal conductor 51 arranged on the top side of the printedcircuit board and the cover plate 21. A knurl 22 (roughened surface) isincorporated into the underside of the projection 21 of the cover plate.Pressing the tips of the knurl, which have a length of up to a few 100μm, into the metallization of the printed circuit board results in animproved electrical connection.

[0028] The printed circuit board has a further projection 42 between thetwo projections 41. Said projection 42 serves for accommodating aconnector 8, as can be seen from FIG. 4. The connector 8 is pushed ontothe projection 42 in the direction of the arrow. Contact elementsarranged in the connector are pushed onto the terminals 52 and 61arranged on both sides of the printed circuit board 4. Conventionalprinted circuit board connectors can be used as the connector.

[0029] The projection 42 is protected against impacts from above andfrom the side by the cover plate projections 21.

[0030]FIG. 5 and FIG. 6 show a different embodiment of the printedcircuit board with only one control terminal 61. Moreover, a knurl 53 isincorporated into the cover plate terminal conductor 51 in the region ofthe cutout 71 for the fixing means. The roughened surface results in animproved electrical connection with respect to the cover plate.

[0031] The printed circuit board comprises further projections 43 in theinterior of the module housing, said further projections serving for thecontact connection of the control busbar. Vertical contact elements (notshown) connect the control terminal conductor 62 to the busbar. Besidesthe cutouts 71 incorporated in the projections 21, it is possible toprovide cutouts for further fixing means.

[0032] Besides the embodiments shown, it is conceivable to use aplurality of projections arranged one beside the other for a pluralityof connectors. A cover plate projection for protecting the respectiveprojection may in each case be provided between the individualconnectors.

[0033] In addition, it is conceivable to provide more than one or twocontrol terminals per printed circuit board projection.

[0034] In particular, exemplary embodiments with three- or multilayerprinted circuit boards, in which each conductor layer comprises at leastone terminal, are also conceivable.

List of Reference Symbols

[0035]1 Power semiconductor circuit

[0036]2 Conductive cover plate, emitter plate

[0037]3 Insulating housing

[0038]4 Insulating printed circuit board

[0039]5, 51 Cover plate terminal conductor

[0040]6, 62 Control terminal conductor

[0041]7 Fixing means

[0042]8 Terminal connector

[0043]9 Conductive baseplate

[0044]21, 41, 42, 43 Projection

[0045]22, 53 Knurl

[0046]52 Cover plate terminal

[0047]61 Control terminal

[0048]71 Cutout for fixing means

1. A power semiconductor module comprising a module housing having aconductive cover plate (2) and a conductive baseplate (9), arrangedessentially parallel to the cover plate, and also an insulating housingwall (3) arranged between the cover plate and the baseplate, a powersemiconductor circuit (1) accommodated in the module housing and havingat least two power terminals, of which one is electrically conductivelyconnected to the cover plate and the other is electrically conductivelyconnected to the baseplate, and at least two terminals (5, 52; 6, 61) ofthe power semiconductor circuit which are led out of the module housing,a first of the at least two terminals (5, 52) being provided for thecontact connection of the cover plate (2), characterized in that aprinted circuit board (4) formed in essentially planar fashion is ledout of the module housing, the printed circuit board (4) being formed inat least two layers, the two terminals being formed as conductors (5, 6)of the printed circuit board (4) and the conductors (5, 6) beingarranged essentially parallel to the base areas of the printed circuitboard (4), and in that the printed circuit board (4) is fixed to thecover plate (2) by fixing means (7) in a force-locking manner, so thatthe cover plate terminal conductor (5) arranged on the side toward thecover plate is electrically conductively connected to the cover plate.2. The power semiconductor module as claimed in claim 1, characterizedin that the fixing means (7) are arranged in the region of theconnection location.
 3. The power semiconductor module as claimed ineither of claims 1 and 2, characterized in that the cover plate (2)and/or the cover plate terminal conductor (5, 51) has acontact-optimizing knurl (22, 53) in the region of the connectionlocation.
 4. The power semiconductor module as claimed in one of claims1 to 3, characterized in that the cover plate (2) and the printedcircuit board (4) each have at least two projections (21), in that arespective projection of the cover plate (21) and of the printed circuitboard (41) are arranged one above the other, in that the fixing means(7) are arranged in the region of the projections (21, 41), in that theprinted circuit board (4) has at least one further projection (42)between the two projections (41), and in that the terminals (52, 61) arearranged on said further projection (42).